The sociocultural approach looks at the role of environmental and social factors on behaviour.  In the study of health psychology, the role of stress on health is a major area of research. One of the key psychologists in the study of stress is Robert Sapolsky.  He studied baboon troops with the goal of seeing how the structure of one's society may have an effect on the HPA axis - that is, the stress response.  In particular, he focused on cortisol levels.

Sapolsky's original research challenged the belief that those in leadership positions have the most stress.  His study of baboon social hierarchies led to the finding that the baboons on the lower rungs of the social hierarchy had higher levels of stress and, therefore, more health problems.  These findings were confirmed in humans in the classic Whitehall study. As you will see below, as a result of the long period of time that Sapolsky studied the baboon, he has refined his theory of the role of social hierarchies. It is not the hierarchy alone that leads to more stress in low-ranking baboons and less in the alpha males, it is the stability of the hierarchy that is important.

Sapolsky carried out a longitudinal study of a wild population of olive baboons in Kenya. The study is an observation of animal behaviour - as well as a natural experiment: he wanted to see the effect of a naturally occurring hierarchy on the health of the baboons.  Considering that there was research triangulation and the research was carried out over a significant amount of time of a single population, the study could be considered a case study. 

Baboons were chosen for several reasons. They have very few predators, so this form of stress is excluded. In addition, they live in troops of 50 - 200 baboons and have a social hierarchy, where the dominant alpha male has more access to food, social grooming and sexual partners.  Finally, they spend time searching for food - but they do not need to spend a lot of time doing this.  Therefore, they have a lot of "free time."  The result is that have a lot of social stressors by interacting with each other in their hierarchical society.  This is very similar to human behaviour and serves as a potential model of the role of social hierarchies and the human stress response.

Baboons were observed in random sequence to avoid bias. Rather than responding to baboons that were "doing something" (known as event sampling), baboons were observed one by one in random order (known as point sampling).

Males were anaesthetized with phencyclidine injected with a syringe fired from a blowgun.  They were darted at the same time of day in order to eliminate circadian fluctuations in hormone levels.  A blood sample was taken within a few minutes to avoid an increase in glucocorticoids as a result of the darting. Mostly male baboons were studied because at any given time 80 per cent of the females were pregnant or lactating -  it would not have been appropriate to anaesthetize them.

The findings showed that subordinate males had higher concentrations of cortisol than dominant males.

Why are high levels of cortisol significant? Over his years of research, he has observed that high levels of cortisol results in hypertension and elevated heart rates and well as high levels of cholesterol, leading to atherosclerosis in low ranking baboons. He has also found that high levels of stress inhibit reproduction in both genders.  In female baboons, this can take the form of delayed puberty, decreased levels of estrogen and progesterone, increased and greater risk of miscarriage.

The sample population was wild. This eliminates the effects of laboratory conditions and results in high ecological validity.

As data was gathered using different research methods, this increases the credibility of the data.

There are questions about the validity of generalizations to human hierarchies. In human hierarchies, there is more mobility - that is, people change their position over time. In addition, the stress response in baboons may not be exactly the same as in humans.

Sapolsky argues that hierarchies alone do not explain cortisol levels; under naturalistic conditions, it is impossible to control for extraneous variables. Such studies have low internal validity.  For example, it may be that the stability of the hierarchy is important to consider. If the hierarchy is unstable, then the alpha males have to fight to maintain their position. In this case, the alpha males have very high levels of cortisol - as high as the lowest-ranking males.

Personality may play a role in cortisol levels. In other words, did the baboons that are able to manage stress better rise to the top of the hierarchy? Or does simply being a the top of the hierarchy moderate cortisol levels?  In other words, the research is correlational and suffers from bidirectional ambiguity.

If you look at the graph above, the year 1984 is rather interesting.  There is not a significant difference between high and low ranking baboons.  What happened?

Sapolsky writes that in 1984 there was a drought in there was a 75% decrease in the food sources available to baboons. During this period, the baboons needed to spend a lot more time looking for food.  The result was a 78% reduction in aggression because the baboons were spending much less time interacting. As a result, significant differences in HPA activity and basal cortisol levels were not observed during that time.

Sapolsky, R. M. (1990). Adrenocortical function, social rank, and personality among wild baboons. Biological Psychiatry, 28(10), 862-878. doi:10.1016/0006-3223(90)90568-m

Sapolsky, R. M. (2005). The Influence of Social Hierarchy on Primate Health. Science, 308(5722), 648-652. doi:10.1126/science.1106477